About 44 minutes before the incident the high-speed train
Sapsan was doing a trial run in the same area. Russian media initially reported that the cause of the derailment was an electrical fault. Witness reports mentioned a "loud bang"; another passenger told reporters in St Petersburg there had been no blast. Early investigation reports did not indicate consensus over the cause. While some reports indicated suspicion of terrorist-related activities, one law enforcement official said that the crater "must be just a pit someone dug out [or could have been] left by an explosive device". Some railway engineers additionally suggested that derailment may have been caused by one or several technical failures without any explosion involved. Responsibility for the attack had first been claimed by far-right nationalists, then by the "
Caucasian Mujahadeen" on orders from
Dokka Umarov, who is considered to be "the leader of the
Islamist insurgency in the
North Caucasus." The attack was claimed to have been part of a series of attacks planned to Russian infrastructure.
Casualties The train was popular with government officials and Russian business executives. ;Notable deaths • – head of •
Sergei Tarasov – chairman of
Rosavtodor, ;Notable injuries • Dmitry Goin – deputy head of Rosreserve • Alexander Poshivay – head of administration of Rosreserve == Second bomb ==